[time-nuts] Another ThunderBolt cabling question

[Chris Albertson]

On Thu, Jun 14, 2012 at 3:59 AM,  <shalimr9 at gmail.com> wrote:
> Acrually the PPS output has very low impedance, so you can probably load it with 5 instruments, each with 50 termination.

My problem with PPS distribution was the fast raise time got "smeared"
by the long cable.   Lots of guesses about why.  Could be reflections
off the end, capacitance in the cable.     The problem is that I want
WAY under 1 microsecond level performance out of a PPS signal.  The
trouble is that the PPS is a single ended signal and the leading edge
is defined by some voltage threshold.   So it is sensitive to noise.
  Two solutions I found (1) differential transmitters and receivers at
each end, like RS-422 type work, or (2) simply move the thunderbolt
physicaly close and use an 18 inch cable.

Take my word for it, the T-Bolt is not able to drive a 100 foot long
twisted pair cable


>
> Not so for the 10MHz though
>
> Didier KO4BB
>
> Sent from my BlackBerry Wireless thingy while I do other things...
>
> -----Original Message-----
> From: "David C. Partridge" <david.partridge at perdrix.co.uk>
> Sender: time-nuts-bounces at febo.com
> Date: Thu, 14 Jun 2012 01:59:42
> To: 'Chris Wilson'<chris at chriswilson.tv>; 'Discussion of precise time and frequency measurement'<time-nuts at febo.com>
> Reply-To: Discussion of precise time and frequency measurement
>        <time-nuts at febo.com>
> Subject: Re: [time-nuts] Another ThunderBolt cabling question
>
> No you can't load the 10MHz (or the PPS) with five instruments in parallel.  You need a distribution amplifier.
>
> Dave
> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On Behalf Of Chris Wilson
> Sent: 13 June 2012 22:33
> To: Discussion of precise time and frequency measurement
> Subject: [time-nuts] Another ThunderBolt cabling question
>
>
>
>  13/06/2012 22:27
>
> About to do the permanent installation, if I bring two leads from the 10 MHz and 1 PPS BNC sockets on the TB to a panel in my shck can i have say 5 BNC sockets on the panel wired in parallel, with the lead from the 10 MHz socket on the TB feeding them all? And a single socket for the 1 PPS? Any need to screen the back of the socket panel, or enclose it in a metal box? Cheers.
>
> Oh, I have been running lady Heather for a while tonight, here's a screen capture, does it look OK, ther's suddenly just two traces appeared? Thanks. http://www.chriswilson.tv/heather.png
>
> --
>       Best Regards,
>                   Chris Wilson.
> mailto: chris at chriswilson.tv
>
>
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-- 

Chris Albertson
Redondo Beach, California